An acidic proteinase found in Schistosoma mansoni adult worms has been suggested to have a role in their nutrition, by digestion of the hemoglobin of host erythrocytes, and utilization of the digestion products. This "hemoglobinase" was first described by Timms and Bueding in 1959, and has subsequently been partially purified and characterized; recently we have shown it to be a thiol proteinase. The objective of this proposal is to purify to homogeneity this proteinase and to determine its chemical and enzymatic properties. The purified proteinase will then be used for two purposes. First, to determine if specific inhibitors of the proteinase affect the viability of the parasite. In vitro culture techniques and radioactive tracers will be used to study the effect of these inhibitors. Second, to prepare antibodies against the purified proteinase, and to determine its possible use in the serodiagnosis and assessment of worm burden in infected individuals. These studies should provide not only basic information on the role of the enzyme in the metabolism of Shistosoma mansoni, but also determine if this proteinase can be useful as a target in the diagnosis and treatment of schistosomiasis.